A Monolithic Implementation of Active Inductor VLQC and Jitter Free Photon Current Detection for Bio-Luminescence SPAD Sensor

An active inductor variable load quenching circuit monolithically implemented for sensing chlorophyll fluorescence and other sensor applications like bioluminescence, tomography, and DNA fingerprints is reported for the first time in this paper. An efficient biosignal acquisition with single-photon counting facility and fast quenching and reset for Single-Photon Avalanche Diode (SPAD) is implemented in 120 nm technology. This is the first ever monolithic active inductor implementation reported for quenching and reset of SPAD pixel. It is faster compared to all previously reported AQRC and variable load quenching circuit (VLQC) monolithic implementations. Along with the principle, a detailed design is presented in 120 nm technology. Analog simulations are done using LT Spice version IV and layout is primed using Microwind 3.1. The results reveals that a 50 ps light pulse with 250 ps dead time, i.e., light pulse with repetition rate of 300 ps can be quenched and detected.